Dig four 12-inch-deep and 10-inch-wide holes where the swing set legs rest so you can insert them into the ground.
Drill two holes at the bottom of each leg with an inward slant so the bolts create an “X” formation when place in the holes. Set one hole about 1/2 inch higher than other so the bolts do not touch each other.
Insert a 12-inch-long galvanized bolt through each hole, so there are two bolts in each swing set leg. Secure the bolts to the legs by sliding on a washer and screwing a nut in place with a wrench.
Set the legs into the holes. Set a level on the swing set to make sure it is leveled before proceeding. Adjust the hole depth to level the swing set, if needed.
Fill one-half of the hole with a quick-setting concrete that you can mix in the hole. Add the appropriate amount of water listed on the package and mix with a stick to combine. Let the concrete cure for four to seven days. Fill the remainder of the hole with dirt and pack it firmly in place with the shovel and stomping the soil with your foot.